- No FAQs found
- ABL Kinase Domain Mutation in CML, Cell-based
- ABO Group and Rh Type
- Acid-Fast Bacillus (AFB) Identification, Sequencing and Stain, Paraffin Block
- ADAMTS13 Activity with Reflex to ADAMTS13 Inhibitor
- Alcohol Metabolites, Quantitative, Urine
- Alpha-Globin Common Mutation Analysis
- Alpha-Globin Gene Deletion or Duplication
- Alpha-Globin Gene Sequencing
- Anti-Müllerian Hormone AssessR™
- Anti-PF4 and Serotonin Release Assay (SRA) for Diagnosing Heparin-induced Thrombocytopenia/Thrombosis (HIT/HITT)
- Antiphospholipid Antibodies
- ASCVD Risk Panel with Score
- Autoimmune Epilepsy Evaluation
- Autoimmune Diseases, Tests for
- Bordetella pertussis toxin (PT) antibody
- B-cell and T-cell Clonality Assays by PCR
- B-Type Natriuretic Peptide (BNP)
- BCR-ABL1 Gene Rearrangement, Quantitative PCR
- Beta-Globin Complete
- Biotin: Interference with Laboratory Assays
- BRCAvantage®, Ashkenazi Jewish Screen
- BRCAvantage®, Rearrangements
- BRCAvantage™, Comprehensive
- BRCAvantage™, Single Site
- CDH1 Sequencing and Deletion/Duplication
- Clostridium difficile Diagnostic Testing
- C1 Inhibitor, Protein and Functional Tests
- Calreticulin (CALR) Mutation Analysis
- Carbapenem Resistant Enterobacteriaceae Culture Screen
- Cardio IQ Lipoprotein Fractionation, Ion Mobility
- CardioIQ® Insulin Resistance Panel with Score
- Cervical Cancer, TERC, FISH
- CFvantage® Cystic Fibrosis Expanded Screen
- Chlamydia trachomatis, TMA
- Chlamydia trachomatis/Neisseria gonorrhoeae RNA, TMA
- Chromosomal Microarray, POC, ClariSure®, Oligo-SNP
- Chromosomal Microarray, Postnatal, ClariSure® Oligo-SNP
- Chromosome Analysis and AFP with Reflex to AChE, Fetal Hgb, Amniotic Fluid
- Chromosome Analysis, Amniotic Fluid
- Chromosome Analysis, Blood
- Chromosome Analysis, Blood with Reflex to Postnatal, ClariSure® Oligo-SNP Array
- Chromosome Analysis, Chorionic Villus Sample
- Chromosome Analysis, High Resolution
- Chromosome Analysis, High Resolution with Reflex to Postnatal, ClariSure® Oligo-SNP Array
- Chromosome Analysis, Mosaicism
- Chromosome Analysis, Neonatal Blood
- Chromosome Analysis, Sister Chromatid Exchange
- Chromosome Analysis, Tissue
- Chromosome DEB Assay for Fanconi anemia
- Chronic Lymphocytic Leukemia (CLL) - Diagnostic and Prognostic Testing
- Culture, Fungus
- Culture, Urine, Routine
- Cystic Fibrosis Screen
- Cytomegalovirus (CMV) and Epstein Barr Virus (EBV) PCR
- Cytomegalovirus (CMV) IgG avidity
- D-Dimer, Quantitative
- Dementia, Secondary Causes
- Dengue Virus Testing
- Diagnosis of Intestinal Parasites
- Drug Testing, General Toxicology (Blood, Urine, or Serum)
- Drug Toxicology Alcohol Metabolite, with Confirmation, Oral Fluid
- Drug Toxicology Monitoring, Oral Fluid Testing
- Factor V (Leiden) Mutation Analysis
- Factor VIII Activity, Clotting
- Familial Hypercholesterolemia (FH) Panel
- Familial Hypercholesterolemia (FH) Single Site
- Familial Mediterranean Fever Mutation Analysis
- First Trimester Screen, hCG
- First Trimester Screen, Hyperglycosylated hCG (h-hCG)
- FISH, Angelman
- FISH, MET Amplification
- FISH, Myeloma, 17p-, rea 14q32 with Reflexes
- FISH, Prader-Willi
- FISH, Prenatal Screen
- No FAQs found
- Helicobacter pylori (H pylori) Antibody Discontinuation
- Heparin, Anti-Xa
- Hepatitis B Surface Antibody, Quantitative
- Hepatitis B Surface Antigen, Quantitative, Monitoring
- Hepatitis C Antibody with Reflex to HCV RNA, PCR with Reflex to Genotype
- Hepatitis C Viral RNA Genotype 1 NS5A Drug-resistance
- Hepatitis C Viral RNA Genotype 3 NS5A Drug Resistance
- Hepatitis C Viral RNA NS3 Drug Resistance
- Hepatitis C Viral RNA, Genotype, LiPA
- Hepatitis C Virus Antibody and RNA Testing
- Hereditary Cancer Panels: MYvantageTM Hereditary Comprehensive Cancer Panel and GIvantageTM Hereditary Colorectal Cancer Panel
- Hereditary Hemochromatosis DNA Mutation Analysis
- Herpes Simplex Virus (HSV) Type-Specific IgG Antibodies
- Herpes Simplex Virus Type 2 (HSV-2) IgG Inhibition, ELISA
- HIV Pre-exposure Prophylaxis (PrEP) Testing
- HIV-1 Coreceptor Tropism, Proviral DNA
- HIV-1 Coreceptor Tropism, Ultradeep Sequencing
- HIV-1 Integrase Genotype
- HIV-1 Resistance, Proviral DNA (RTI, PI, Integrase Inhibitors)
- HIV-1/2 Antigen and Antibodies, Fourth Generation, with Reflexes
- HPV mRNA E6/E7
- Infliximab and Adalimumab Drug and Anti-drug Antibody Testing
- Influenza A and B Antigen, Immunoassay
- Influenza Type A and B Antibodies
- Insulin, Intact, LC/MS/MS
- Integrated Screen, Part 1
- Integrated Screen, Part 2
- Intrinsic Factor Blocking Antibody
- No FAQs found
- No FAQs found
- LDL Cholesterol Calculations
- LeukoVantage® Myeloid Neoplasm Mutation Panels
- Lupus Anticoagulant (LA) Evaluation with Reflex
- Maternal Serum AFP
- Melanoma, BRAF V600E and V600K Mutation Analysis, THxID®
- Metanephrines, Fractionated, Free, LC/MS/MS, Plasma
- Methylenetetrahydrofolate Reductase (MTHFR), DNA Analysis
- Microalbumin (Urinary Albumin Excretion)
- Myeloproliferative Neoplasm Diagnosis: Molecular Evaluation
- No FAQs found
- Pain Management and CYP2D6/CYP2C19
- Pain Management Antidepressants, With Confirmation, Urine
- Pain Management Antipsychotics, With Confirmation, Serum and Urine
- Pain Management, Naltrexone, Quantitative, Urine
- Partial Thromboplastin Time, Activated (aPTT)
- Penta Screen
- Pharmacogenomics Panel
- PIK3CA Mutation Analysis
- Platelet Antibody Screen (Indirect)
- PNH with FLAER (High Sensitivity)
- Prothrombin Time with INR
- PTH, Intact and Calcium
- Streptococcus pneumoniae (Pneumococcal) Antibody Tests
- Saccharomyces cerevisiae Antibodies (ASCA) (IgG, IgA)
- Sequential Integrated Screen, Part 1
- Sequential Integrated Screen, Part 2
- Serum Integrated Screen, Part 1
- Serum Integrated Screen, Part 2
- Serum Pregnancy Tests
- Sickle Cell Screen
- Stepwise, Part 1
- Stepwise, Part 2
- SureSwab® Trichomonas vaginalis RNA, Qualitative TMA
- SureSwab®, Candidiasis, PCR
- TP53 Sequencing and Deletion/Duplication
- T4, Free
- Tamoxifen and Metabolites, LC-MS/MS
- Testosterone Testing
- Total Testosterone, LC/MS/MS
- Triple Screen
- No FAQs found
- No FAQs found
- No FAQs found
Omega-3 and -6 Fatty Acids, PlasmaTest code(s) 91001
The FAQ information attached by the previously provided link was retired on 8/18/2015. The link continues to be available for your historic reference. Current FAQs can be viewed at QuestDiagnostics.com/FAQs.
Question 1. What is the clinical significance of the EPA/AA ratio?
High levels of eicosapentaenoic acid (EPA) and low levels of arachidonic acid (AA) are associated with fewer CVD events.
- In the JELIS investigation, a plasma EPA/AA ratio >0.75 was associated with a significantly reduced risk for coronary events.1
- In 1,050 patients with a prior myocardial infarction (MI), supplementation with 1,800 mg/day EPA increased the EPA/AA ratio from 0.6 to 1.3.2 Those patients who achieved an EPA/AA ratio ≥1.06, compared to those with an EPA/AA ≤0.55, had a significant reduction in cardiac death and MI.2
Question 2. How were the risk cut points for the omega-3 index determined?
Multiple studies of patients who were either at risk of cardiovascular disease (CVD) or who had had a non-fatal MI showed that individuals with the highest omega-3 levels (typically the highest quartile) are at reduced risk of CVD events, compared with those in lowest omega-3 quartile. In the Physicians’ Health Study, higher blood levels of EPA+DHA+DSA, as a percent of total fatty acids, were associated with a significant reduction (p=0.007) in sudden death from cardiac causes after adjustment for potential confounders.3
The risk cut points used in our plasma-based omega-3 index test are based on quartiles determined by our testing of samples from apparently healthy adults. Plasma phospholipid omega-3 index levels in the bottom quartile (<1.1%) are classified as high risk; the central 2 quartiles (1.1% to 3.3%) as moderate risk, and the highest quartile (>3.3%) as low risk.
Question 3. What sample type and collection conditions are required for the plasma omega-3 and omega-6 fatty acid test (test code 91001)?
The patient should be fasting for 8 to 12 hours before the sample collection. Collect sample in lavender-top (EDTA) tube and separate the plasma from the cells. Ship 2.0 mL (0.4 mL minimum) of EDTA plasma at ambient temperature, refrigerated, or frozen.
Question 4. What effect can fish oil supplementation have on advanced lipoprotein measurements?
Omega-3 supplementation has been reported to significantly improve the lipoprotein profile: specifically, it substantially increased HDL2b and LDL peak particle size.4
Question 5. What is the difference between plasma-based and RBC membrane-based methods for measuring fatty acids?
In both methods, fatty acids are identified by comparison with known standards, and their composition is reported as weight percent of total phospholipid fatty acids. The sum of EPA plus DHA, as a percentage of total phospholipid fatty acids measured, is reported as the omega-3 index.
The Quest Diagnostics test is plasma-based and determines the fatty acid concentration in plasma phospholipids using a liquid chromatography, tandem mass spectrometry (LC/MS/MS) method. Phospholipids are extracted and hydrolyzed before LC/MS/MS analysis. Since this plasma-based method may be influenced by recent diet or supplement use, we recommend patients be in a fasting state when samples are collected.
In an RBC-based method, fatty acids from red blood cell phospholipids are hydrolyzed, esterified, extracted with hexane, and analyzed by flame ionization gas chromatography.
Question 6. What is the clinical difference between results obtained using the Quest Diagnostics plasma-based method versus the RBC-based method?
With either method, a higher omega-3 index is associated with decreased cardiovascular disease risk.
The plasma-based method has been used in multiple studies. A plasma EPA concentration ≥150 µg/mL (compared to <87 µg/mL) was associated with a significant 20% reduction in major coronary events in 15,534 subjects in the JELIS investigation.1
RBC-based methods have also been used in several clinical trials. In these studies, patients with a high omega-3 index were atlow risk of acute coronary syndrome, while those with medium levels were at intermediate risk and those with low levels were at high risk, all relative to controls.5
- Itakura H, et al. J Atheroscler Thromb. 2011;18:99-107.
- Matsuzaki M, et al. Circ J. 2009;73:1283-1290.
- Albert CM, et al. N Engl J Med. 2002;346:1113-1118.
- Wooten JS, et al. J Appl Physiol. 2009;107:794-800.
- Block RC, et al. Atherosclerosis. 2008;197:821-828.
- Glaser C, et al. Metabolism. 2010;59:993-999.
- Lu Y, et al. Am J Clin Nutr. 2010;92:258-265.
- Martinelli N, et al. Am J Clin Nutr. 2008;88:941-949.
- Pottala JV, et al. Circ Cardiovasc Qual Outcomes. 2010;3:406-412.
- Raatz SK, et al. J Am Diet Assoc. 2009;109:1076-1081.